Buoys are used to mark a location in a body of water. Locations are marked for a variety of reasons. Fishermen may deploy buoys to mark a location where the fish are biting. Fisherman may mark a location where the lake bottom topography seems likely to attract fish, for example. Buoys may be used to mark hazards for boats navigating a lake. For example, a shallow region in a lake may be marked by buoys surrounding the shallow region. A large boulder projecting just beneath a surface of a lake may be marked by a buoy. Buoys are used to mark a circumference of a swimming regions. Lifeguards, may be stationed so as to be able to rescue swimmers swimming in the marked swimming region. Swimmers may know the extent of the life-guarded region. Rescue teams may mark a perimeter of a search area. For example, the location of a capsized water craft may be marked with a buoy, and a corresponding perimeter may be marked to set up a search grid.
Buoys may be fixed in a location by being tethered to an anchor. For example, a buoy may be connected to a chain or a rope, which in turn may connect to an anchor resting on a bottom surface of the body of water. In some embodiments, the length of the tether may be customized to correspond to a depth at a location of deployment.